68 Buick California GS HVAC issue

[Guest Tonino]

My 68 California GS with manual AC has a small vacuum plug (manifold?) plugged into the rear of the HTR/VENT/AC/REC thumbwheel switch on the dash.

It has 3 ports on it - one of which has a Tee - one vac line goes to port two on the heater blower switch, and the other goes to the main outside/inside

air door behind the passenger kick panel. I need to replace the little plug but need to know the part number and/or the correct part description.

Better still, if anyone has one of these in working condition or NOS, I'll buy it.

Thanks

Tonino